Rotary industrial driers

ABSTRACT

A rotary drier and cooler having cylindrical drums resting on sets of pneumatic tires is driven in rotation about horizontal axes. The hot drying gas is generated in a hearth which is mounted on a carriage travelling on rails parallel to the axes of the drums. Filter screens rotate with the drums to clean the hot drying gas and the cooling gas flowing in a countercurrent through the cooler. Hooded helical ducts convey the material from the drier to the cooler.

United States Patent Inventor Guy Quesnel GlLFranee Appl. No. 800,148 Filed Feb. 18, 1969 Patented Aug. 17, 1971 Assignee Stein & Roubnlx Paris, France Priority Feb. 22, 1968 France 140827 ROTARY INDUSTRIAL DRIERS 4 Claims, 2 Drawing Figs.

0.8. CI 34/109, 34/126. 263/32, 259/175, 259/81 Int. r F26b 13/18 Field of Search 34/108, 109,l25129,13,l13,12l,l30;263/33, 32; 259/177, 175

[56] References Cited U NITED STA TES PATENTS 2,870,547 H1959 Teichman 34/129 3,016,232 1/1962 Domenighetti 259/177 3,033,057 5/1962 Gray... 259/175 X 3,051,193 9/1962 Wright 1. 34/128 X 3,360,868 H1968 Arnold 34/13 Primary Examiner-FrederiCk L. Matteson Assistant Examiner-Theophil W. Streule Atl0rney-Waters, Roditi. Schwartz & N issen ABSTRACT: A rotary drier and cooler having cylindrical drums resting on sets of pneumatic tires is driven in rotation about horizontal axes. The hot drying gas is generated in a hearth which is mounted on a carriage travelling on rails parallel to the axes of the drums. Filter screens rotate with the drums to clean the hot drying gas and the cooling gas flowing in a countercurrent through the cooler. Hooded helical ducts convey the material from the drier t0 the cooler.

PATENTEU AUG 1 71971 SHEET 1 OF 2 ROTARY INDUSTRIAL DRIERS The present invention relates to rotary industrial driers, and derived apparatus such as drier-coolers. It has for object more particularly improvements in apparatus of this type.

Conventionally, rotary driers are constituted by a drum supported by metallic friction rollers and driven in rotation through the intermediary of a toothed ring and a pinion actuated by a motor. 7

According to a first improvement, the cylindrical drum is caused to rest on pneumatic tires which effect the driving at the same time as the support.

Preferably, a rolling track solid with the drum and cooperating with the pneumatic tires enables the latter to be withdrawn from the effects of the heat, at the same time as facilitating the solution of the problems of driving, since the said rolling track has the effect of increasing the driving diameter, hence of reducing the torque to be transmitted by the pneumatic tires.

In accordance with another feature of the invention the "heating hearth serving to generate the hot gases used in the drier is constituted by a drum which is supported by a carriage movable on rails parallel to the axis of rotation of the said horizontally installed drum.

The assembly of carriage and drum constituting the hearth may be equipped with various members necessary for the preparation of the fuel, that is to say, the pumps, filters, working reservoirs, etc. as well as the feeding hopper of the drier. Such an arrangement with fixed hearth has the advantage of permitting easy access into the drier.

In the case of a drier-cooler, the drum is extended by a cylindrical body in which the dried product is cooled, the hot gases circulating parallel to the product in the drier properly speaking, and the cold gases circulating in counterflow to the product in the cooler being evacuated together substantially at the level ofthe junction of the cylindrical body and the drum.

According to another feature of the invention the passage of the dried pulverulent produce from the drier to the cooler takes place through the intermediary of hooded ducts of helical form in which the product falls by overflow and proceeds sheltered from the gaseous currents.

in order to free the hot gases from dust, in a drier alone or at the outlet of a drier-cooler apparatus, and in the latter case likewise to free the cold gases from the dust that they carry, systems of filter screens that turn with the apparatus are provided. These screens allow the gases to pass but retain the dust, which under the action of the rotation is ejected at the periphery and falls from there back on to the product in motion, that is to say in the interior in the case ofa drier only or in the helical duct in the case of a drier-cooler. Other features also forming part of the invention will appear in the course of the description that will follow with the accompanying drawing in support, given mainly by way of example, and in which:

FIG. 1 is a view in longitudinal section of a drier-cooler; and

FIG. 2 is a view in cross section on the line 11-" of FIG. 1.

Following what has been said above, it is clear that one may easily deduce from the description of a drier-cooler the features also capable of being applied to a drier alone. For this reason, and in order to avoid repetition, only the case of the more complete apparatus, that is to say the drier-cooler, has been illustrated and will be described.

The part of the apparatus intended for drying a moist pulverulent product comprises a cylindrical drum 1 with horizontal axis, which rests on a set of pnuematic tires such as 2a, 2bwhich effect both the support and the rotation of the said drum. For this purpose at least one of the sets of pneumatic tires, say 2a, is a driving set, the shaft of which is driven by the shaft 3 of an electric motor 4 through the intermediary of a direction changing gearing.

Preferably a rolling track 5 is fixed to the drum 1 and cooperates with the pneumatic tires. Such a rolling track, having a diameter greater than that of the drum, offers numerous advantages and permits in particular the withdrawal of the pneumatic tires from the effects of heat while giving the possibility of resolving more easily the problems of driving the drum in rotation since the larger diameter of the rolling track reduces the torque to be transmitted by the driving sets of pneumatic tires. Further, friction rollers 6 on vertical axes, which may be also pneumatic tires and which serve for taking up lateral play of the drum, may bear against the lateral surface Sa of the rolling track.

The drum is equipped internally with an insulating lining 7 protected by steel wearing plates 8 previously bent to form elements for driving the product to be dried in rotation. This insulating lining 7 has the double effect of improving the thermal efficiency of the drier and of withdrawing the drum 1 and hence the pneumatic tires from the action of heat.

At one end of the drum, on the feeding side, is located the heating hearth serving to generate the hot gases used in the drier. This hearth is constituted by a drum 9, equipped internally with refractory materials lllnecessary for its protection. It is supported by a carriage 11 furnished with wheels 12 which can move on two rails 13 parallel to the axis of rotation of the drum 1 of the horizontally installed drier. The hearth is equipped with at least one burner 14 which may be an oil or gas burner, and the drum 9 is formed at its upper part in such manner as to support the hopper 15 for feeding the drier. Further, the carriage 11 may be arranged to carry the various members necessary for the preparation of fuel used in the burner 14, that is to say, the pumps, filters, working reservoirs,

etc.

' It is seen that the arrangement of the hearth such as described permits easy access into the drier.

At the opposite end of the hearth the rotary drier comprises a dust removing device having filter screens. The drying gases pass through the filter screens 16 which turn with the drum and which retain the dust. The gases from which the dust has been removed are drawn into an annular passage 17, then into a ring 18 by a fan 19 before being ejected to the atmosphere via a stack or chimney 20. The dust is ejected or exhausted under the action of the rotation to the periphery of the drum, from which it falls back on to the moving product.

The device for advancing the product is constituted by vanes suitably arranged in the interior of the drier.

If the apparatus envisaged is a simple drier, the dried product, with which is mixed the fine dust retained by the filter screens, is evacuated by suitable means.

In the case of a drier-cooler, the drum 1 is extended by a cylindrical body 21 welded or fixed to the said drum and formed in such a manner that the product may pass from one to the other. A set of pneumatic tires such as 22 supports the drives the cylindrical body 21, being in contact with a rolling track 23. The set of pneumatic tires 22 is driven in the same manner described before, from an electric motor 24. It should be noted that the driving of the sets of pneumatic tires is performed by substantially similar independent motors which share the driving torques without the interposition of a mechanical differential connection.

The drier is furnished internallywith an insulating material 25 protected by steel wearing plates 26 bent in such manner as to form lifting devices suitable for effecting desirable dispersion of the product in the current of air. The cold air is introduced via adjustable openings 27 in the end 28 of the drier and circulate in counterflow to the product. In the vicinity of the drier is provided filter screens 29 likewise driven in rotation and playing the same part as the filter screens 16. The cold air freed from dust is evacuated with the hot gases freed from dust, via the annular passage 17.

The passage of the product from, the drier to the cooler is effected in the following manner: at the end of the drying part the product falls by overflowing into hooded ducts 30 of helical form, and passes into the cooling part. These hooded ducts are constituted by steel plates the height of which is equal to the difference between the internal diameter of the drum 1 with its internal lining and the external diameter of the cylindrical body 21.

The cooler ends in a wall 31 for receiving the product; the latter passes through peripheral openings 32 and falls into the well 31.

The apparatus that has just been described can be caused to turn at a relatively high speed, in such manner as to multiply the cascading effect and improve the exchanges. Thus, the speed may be between 40 percent of the critical speed and a speed above the critical speed, in such manner as to permit a self-lining effect of the drum of the drier to be obtained and, eventually, ofthe cooler.

It goes without saying that the practical form described has been given mainly by way of example and that it may receive numerous modifications without thereby exceeding the scope of the present invention.

l claim:

1. A rotary drier comprising a cylindrical drying drum, sup port means for said drum comprising pneumatic tires on which said drum rests, means mounting said tires for rotation about axes generally parallel to the axis of said drum, means for driving said tires in rotation whereby said drum is rotated, a heating hearth for generating hot gases to effect the drying, said heating hearth being constituted by a second drum, a carriage supporting said second drum, and rails extending parallel to the axis of the first drum and movably supporting said carriage for axial movement toward and away from said drying drum said drier further comprising a cooling drum axially aligned with and connected to said drying drum for rotation with the latter, means for circulating cold air through said cooling drum in counterflow to the material to be dried, and respective filter screens associated with said drying drum and cooling drum and interposed between the latter drums for rotation therewith, the filter screen associated with said drying drum being disposed at the outlet end of the latter.

2. A rotary drier as claimed in claim 1 wherein said drying drum carries a rolling track which cooperates with said tires.

3. A rotary drier as claimed in claim 1 including hooded ducts of helical form disposed between said drying drum and said cooling drum to convey the material being dried, said material falling into said ducts by overflow and being protected from gaseous currents thereby.

4. A rotary drier as claimed in claim 1 including further pneumatic tires supporting the cooling drum, and independent electric motors driving said pneumatic tires supporting the drying drum and said further pneumatic tires supporting the cooling drum. 

1. A rotary drier comprising a cylindrical drying drum, support means for said drum comprising pneumatic tires on which said drum rests, means mounting said tires for rotation about axes generally parallel to the axis of said drum, means for driving said tires in rotation whereby said drum is rotated, a heating hearth for generating hot gases to effect the drying, said heating hearth being constituted by a second drum, a carriage supporting said second drum, and rails extending parallel to the axis of the first drum and movably supporting said carriage for axial movement toward and away from said drying drum said drier further comprising a cooling drum axially aligned with and connected to said drying drum for rotation with the latter, means for circulating cold air through said cooling drum in counterflow to the material to be dried, and respective filter screens associated with said drying drum and cooling drum and interposed between the latter drums for rotation therewith, the filter screen associated with said drying drum being disposed at the outlet end of the latter.
 2. A rotary drier as claimed in claim 1 wherein said drying drum carries a rolling track which cooperates with said tires.
 3. A rotary drier as claimed in claim 1 including hooded ducts of helical form disposed between said drying drum and said cooling drum to convey the material being dried, said material falling into said ducts by overflow and being protected from gaseous currents thereby.
 4. A rotary drier as claimed in claim 1 including further pneumatic tires supporting the cooling drum, and independent electric motors driving said pneumatic tires supporting the drying drum and said further pneumatic tires supporting tHe cooling drum. 